Preview
Hüseyin Akbulut, MSc (2026). Back Extension Endurance Test (Sorensen Test): Protocol and Application. Sporeus. Retrieved, November 9, 2026. https://sporeus.com/en/egzersiz-testleri-en/back-extension-endurance-test-sorensen/
Measures: Back extensor endurance
Table of Contents
Difficulty: Moderate | Category: Strength
Protocol
The Sorensen Back Extension Test, described by Biering-Sørensen (1984), measures static endurance of the back extensor muscles (erector spinae, multifidus).
Preparation: The participant lies prone on a couch or hyperextension bench with the upper trunk (from the anterior superior iliac spine upwards) unsupported. Pelvis, knees and ankles are secured with straps. Arms are crossed over the chest.
Test Procedure: The participant holds the upper trunk horizontal (parallel to the floor). The stopwatch starts when the position is taken. The test ends when the upper trunk drops clearly below horizontal or the participant gives up.
Data Recording: Duration is recorded in seconds.
Interpretation: Biering-Sørensen (1984) reported that good extensor endurance in men was associated with not developing first-time low back pain over the following year. McGill et al. (1999) reported mean times of about 161 s in men and 185 s in women in healthy young adults.
Post-Test: Cool down with gentle back and hip movements.
Formula
Flexion/extension ratio = trunk flexion_s / Sorensen_s; below 1.0 expected
Equipment Required
Roman chair or raised table, stopwatch, stabilisation strap or partner
Interpretation
There is no single widely accepted normative table for this test. Results are best interpreted against the person’s previous measurements with the same protocol and equipment (and, where relevant, left-right comparison).
Practical Applications
The Sorensen test is a widely used protocol in low back health screening, occupational assessment and monitoring of sports rehabilitation.
Limitations
It may aggravate symptoms in people with current low back pain. The need for a bench and straps limits field use.
Related Tests: Trunk Flexion Endurance Test, Side Plank Test, Plank Hold Test
Sources: Biering-Sørensen F, 1984, Spine; McGill SM et al., 1999, Arch Phys Med Rehabil
Hüseyin Akbulut is the founder of Sporeus and author of THRESHOLD (EŞİK), a 540-page Turkish-language book on endurance science.
- 540pp THRESHOLD Book
- MSc Sport Sciences
- Marmara University
Protocol The Sorensen Back Extension Test, described by Biering-Sørensen (1984), measures static endurance of the back extensor muscles (erector spinae, multifidus). Preparation: The participant lies prone on a couch or hyperextension bench with the upper trunk (from the anterior superior iliac spine upwards) unsupported. Pelvis, knees and ankles are secured with straps. Arms are crossed over the chest. Test Procedure: The participant holds the upper trunk horizontal (parallel to the floor). The stopwatch starts when the position is taken. The test ends when the upper trunk drops clearly below horizontal or the participant gives up. Data Recording: Duration is recorded in seconds. Interpretation: Biering-Sørensen (1984) reported that good extensor endurance in men was associated with not developing first-time low back pain over the following year. McGill et al. (1999) reported mean times of about 161 s in men and 185 s in women in healthy young adults. Post-Test: Cool down with gentle back and hip movements. Formula
Flexion/extension ratio = trunk flexion_s / Sorensen_s; below 1.0 expected
Equipment Required
Roman chair or raised table, stopwatch, stabilisation strap or partner
Interpretation
There is no single widely accepted normative table for this test. Results are best interpreted against the person's previous measurements with the same protocol and equipment (and, where relevant, left-right comparison).
